Paints are typically liquids, which are useful for application to a substrate, such as wood, metal, glass, ceramics, fiberglass, composite materials, cardboard, corrugated board, paper, textiles, non-woven materials, plastic, foam, tape or a combination thereof, in a thin layer. Paints are typically used to protect the surface of the substrate from elemental damage and/or physical damage. They are also commonly used for decoration and aesthetic purposes, and find very broad commercial use as well as a variety of uses in the home. Paints, their formulations, ingredients, additives and processing conditions are generally described in Kirk-Othmer-Paint; pg. 1049-1069, Vol. 17; 1996, by Arthur A. Leman, the disclosure of which is incorporated herein in its entirety.
For many years, there has been a need in the paint industry for a paint that is capable of preventing growth of microbes, such as mould and bacteria, on walls and other painted surfaces. Indoors, moulds can be a health hazard as well as an aesthetic problem. Additionally, a paint that has antibacterial qualities would be desirable, especially in hospitals, kitchens, and meat processing rooms. Until now, it has been difficult to produce a paint with anti-microbial activity which also has low toxicity to humans.
A number of paints claim to have anti-bacterial, anti-fungal, anti-yeast and/or anti-viral activity. However, many of these paints suffer from associated problems that either affect their visual appeal and/or create potential toxicological health hazards. For example, metal pyrithione compounds, such as zinc pyrithione, have been used in latex paint as long lasting anti-fungal compounds with low human toxicity. However, it is well known in the paint manufacturing industry that the effective amount of zinc pyrithione is approximately 0.5% v/v, but greater than about 0.4% v/v is very difficult to mix into typical paint bases or binders. Moreover, zinc pyrithione is sensitive to ultraviolet light and consequently tends to experience loss of its antimicrobial properties upon exposure to sunlight. Furthermore, zinc pyrithione yellows after a period of time in the presence of sunlight, which affects the color of a paint in which it is present.
The present invention relates to an antimicrobial paint that overcomes or at least alleviates some of the problems associated with so-called antimicrobial paints previously in use.